1. Field of the Invention
This invention relates to an instrument and method for circular surgical stapling of hollow body organs, and more particularly, to an improved anvil assembly having a tether line for retrieving a disengaged anvil portion from the hollow body organ after stapling.
2. Description of the Prior Art
There are several known types of surgical staplers in which the stapling function takes place at a location which is relatively remote from the location at which the stapler is held and actuated by the operator. One example of such a stapler is the circular anastomosis surgical stapler shown illustratively in Conta et al. U.S. Pat. No. 4,304,236. Typically, in instruments of this type exemplified by this reference, tissue to be stapled is clamped between an anvil assembly and a staple holding assembly, both of which are located at the distal end of the instrument. The clamped tissue is stapled by driving one or more staples from the staple holding assembly so that the ends of the staples pass through the tissue and are clinched by contact with the anvil assembly. The forces required to operate the instrument are applied by the operator of the instrument to one or more actuator elements located at or near the proximal end of the instrument. The distal and proximal portions of the instrument are joined by a longitudinal connecting shaft structure along which the actuating forces and motions are transmitted to the distal operating elements.
In use in the typical application of joining two intestinal sections together, instruments of the type mentioned above are first positioned so that the staple holding assembly is inside the end of a first intestinal section and the anvil assembly is inside the end of a second intestinal section. The severed ends of the intestinal sections are typically secured by purse strings and then clamped between the staple holding assembly and the anvil assembly. The instrument is then operated so as to drive staples from the staple holding assembly through the clamped tissue, and against an anvil portion of the anvil assembly. The same operation of the instrument which drives the staples also drives a knife to cut away the waste or excess tissue inside the annular array of staples and thereby clear the lumen between the connected organ sections.
The joining of the intestinal sections now complete, the instrument can be removed. To remove the instrument from the stapled tissue, the anvil assembly is typically moved away from the staple holding assembly so that the tissue is no longer clamped by the instrument. The entire instrument is then pulled out of the first intestinal section.
In withdrawing the instrument, the anvil portion of the anvil assembly is withdrawn past the stapled tissue. Since the outer circumferential surface of the anvil has a diameter greater than that of the intestinal sections at the point where the intestinal sections have been recently stapled, the stapled tissue is stretched by the contact of the anvil with the stapled tissue. Reducing contact between the full circumference of the anvil and the stapled tissue, can decrease the degree of stretching of the newly stapled tissue.
In view of the foregoing, there is a need to provide an anvil assembly, and method of using same, which facilitates withdrawal of the anvil assembly from a hollow body organ. There is also a need for an anvil assembly which minimizes stretching of tissue upon withdrawal.